html body {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
  box-sizing: border-box;
}

html body .form {
  width: 50vw;
  margin-bottom: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

html body .form .row {
  display: flex;
  align-items: center;
  margin-bottom: 10px;
}

html body .form .row .row-hd {
  width: 4em;
}

html body .form .row .row-bd {
  width: 20em;
}

html body .form .row .row-bd input {
  width: 100%;
  height: 100%;
}

html body .form .btn {
  width: 10em;
  text-align: center;
  height: 30px;
  line-height: 30px;
  border-radius: 5px;
  background-color: darkcyan;
  color: #fff;
}
